Dragging text from gtk4 to other applications
Tested in a system with the X11 backend.
Start one instance of gtk4's tests/testdnd and one instance of gtk3's tests/testdnd. Drag text from the drag label in one instance to the drop label in the other instance.
It's possible to drag text from gtk3 to gtk4.
When text is dragged from gtk4 to gtk3, an empty string is sometimes received,
Received "" in label
but usually nothing is received (no output from the receiving window).
Dragging between gtk4 and gedit works equivalently. It's possible to drag text from gedit to gtk4, but not from gtk4 to gedit.